1. Field of the Invention
This invention pertains generally to charge storage devices, and more particularly to a field configurable ion-doped capacitor.
2. Description of Related Art
The rapidly growing markets for hand held computers, mobile communications and wireless networking have created a demand for small sized, low energy consuming, high-performance circuits. Circuit elements such as capacitors are well known and understood in circuit design and are essential design elements.
A capacitor is considered to be a “passive” circuit element because it does not actively affect the electrical current. The typical capacitor consists of two isolated conductive plates separated by a dielectric with a charge +Q on one conductive plate an equal but opposite charge −Q stored on the other plate. Common dielectric materials include paper, plastic, glass and ceramics. The dielectric essentially insulates the plates and limits any transfer of charge between the plates. The capacitance of a given set of conductor plates depends only upon their geometry (i.e. the shape of the plates and the distance between the plates) and on the nature of the dielectric placed between the plates. The charge that is “stored” in the capacitor has been shown to be proportional to the potential difference between the two conductors.
The basic configuration of conventional capacitors and their capabilities have remained the same for many years. Recent attempts to expand or improve the capabilities of capacitors have met with limited success. For example, nonvolatile capacitors have been made from ferroelectric materials, but their capacitances can only be switched between bistable digital “0” and “1” states. The capacitances of reverse-biased semiconductor diodes or the gate capacitances of MOSFET's (varactors) can be modified by the voltage V, but the capacitance modification is volatile and cannot be memorized after the voltage is removed.
Accordingly, there is a need for a capacitor that can be small in size, has low energy consumption and has a capacitance that can be selectively modified. The present invention satisfies this need, as well as others, and generally overcomes the deficiencies of the prior art.